1. Field of the Invention
The present invention relates to a numerical controller, and particularly, to a numerical controller with a function of automatically switching an acceleration/deceleration setting in accordance with machining content or a machining state.
2. Description of the Related Art
In machining with a machine tool, the related art such as JP 2004-237441 A and JP 06-155233 A is known as a technology of automatically setting a machining condition suitable for each machining, for example, to shorten a cycle time.
A technology disclosed in JP 2004-237441 A relates to a device which auto-generates a machining program, and a machining condition for minimizing “total cutting time X a tool wear cost per use” is obtained on the basis of an optimized tool path and tool design information including a pre-set cost of each tool and information of a life characteristic in the course of generating the machining program. Since a spindle rotation rate or a feed rate is handled as the machining condition and an acceleration/deceleration is not mentioned in this document, it is not intended to shorten the cycle time through a change of the acceleration/deceleration setting.
In a technology disclosed in JP 06-155233 A, the machining condition for shortening a machining time is obtained with respect to a machining program output by an automatic programming device in consideration of machining capability of each tool according to material of a workpiece or a limitation of the capability of the machine tool used for the machining. The machining condition is automatically calculated by a computer with reference to machining data in which the machining capability of the tool is described and a machine file in which the machining capability of a machine is described. Since the spindle rotation rate or the feed rate is handled as the machining condition and the acceleration/deceleration is not mentioned also in this document, it is not intended to shorten the cycle time through the change of the acceleration/deceleration setting.
The acceleration/deceleration setting such as a magnitude of the acceleration and an acceleration-change time is an important factor to determine a machining rate or a machining accuracy. For example, a drilling is less affected even by a high acceleration, but an end mill bottom surface machining is considerably affected by an increase of the acceleration and thus it is necessary to reduce the acceleration. As for setting of the acceleration, in the machining less affected even by the setting of the high acceleration, the high acceleration is set in order to shorten the cycle time (speed priority setting), and in a case where an accuracy is not improved without the setting of a low acceleration, it is desired to set the low acceleration (accuracy priority setting).
However, the related art disclosed in JP 2004-237441 A and JP 06-155233 A is insufficient in that the machining rate or the machining accuracy cannot be appropriately set since an automatic switch of the acceleration/deceleration setting is not considered as a method of setting the machining condition. In addition, in a case where a switch of the acceleration/deceleration setting is not performed automatically, a method in which a command to switch the acceleration/deceleration setting is included in the machining program is used as a method of switching the acceleration, but the method lays a large burden on an operator.